1. Field of the Invention
The present invention in general relates to a control circuit of a power converter, and more particularly, to a synchronous rectifying control circuit for a power converter.
2. Description of Related Art
An offline power converter includes a power transformer to provide isolation from AC line input to the output of the power converter for safety. In recent development, applying the synchronous rectifier in the secondary side of the transformer is to achieve a high efficiency conversion for power converters, such as “Control circuit associated with saturable inductor operated as synchronous rectifier forward power converter” by Yang, U.S. Pat. No. 7,173,835. However, the disadvantage of this prior art is an additional power consumptions caused by saturable inductors and/or current-sense devices. The saturable inductor and the current-sense device are needed to facilitate the synchronous rectifier operated in both continuous mode and discontinuous mode operations.